As an antenna used for a radio equipment, a patch antenna is most common, which includes a dielectric block, a radiating electrode formed on one main surface thereof, a ground electrode formed on the other main surface of a dielectric block, and a feed pin arranged so as to penetrate the dielectric block from the one main surface to the other main surface, as disclosed in Japanese Patent Application Laid-Open No. 2003-289219.
In the antenna disclosed in Japanese Patent Application Laid-Open No. 2003-289219, however, since it has such a configuration that power is fed to the radiating electrode by the feed pin penetrating the dielectric block, not only surface mounting to a printed circuit board or the like is difficult, but also the feed pin and a member such as a double-sided tape for fixation are necessary, thereby causing a problem in that the number of parts increases. Further, since a soldering step is required for fixing the feed pin, the production cost also increases.
As a method for solving these problems, Japanese Patent Application Laid-Open No. H11-74721 proposes a method in which a feed electrode is provided, with a predetermined gap between the radiating electrode and the feed electrode, on one of the main surfaces of the dielectric block (on a surface where the radiating electrode is formed) According to this configuration, since it is not necessary to use the feed pin penetrating the dielectric block, surface mounting becomes easy, thereby enabling miniaturization and reduction in height of the radio equipment.
In the surface mounted antenna disclosed in Japanese Patent Application Laid-Open No. H11-74721, however, since the feed electrode is provided on one main surface of the dielectric block (on a surface where the radiating electrode is formed), the area of the main surface of the dielectric block increases as much as this portion, thereby causing a problem in that the mounting area increases. Further, when circularly polarized waves are to be radiated, with the surface mounted antenna disclosed in Japanese Patent Application Laid-Open No. H11-74721, since a conductor pattern for discharging right-hand polarized waves and a conductor pattern for discharging left-hand polarized waves are different from each other on one of the main surfaces of the dielectric block, it is necessary to form these conductor patterns (the radiating electrode and the feed electrode) on one of the main surfaces of the dielectric block by using different screen masks.